<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <ul>
        <li>html</li>
        <li>css</li>
        <li>javascript</li>
    </ul>
    <script src="./jquery-3.6.0.js"></script>
    <script>
        //下标
        let li1 = $("ul li:nth-child(1)")[0]
        li1.style.color = "red"

        //get获取得到某个下标的dom节点
        let li2 = $("ul li:nth-child(2)").get(0)
        li2.style.color = "blue"

        //*********dom节点***********jq
        let li3 = document.querySelector("ul li:nth-child(3)")
        //语法$(dom节点)
        $(li3).css("color", "green")
    </script>
</body>

</html>